JP2000228387A - Wet cleaner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wet cleaner which can eliminate impurities such as a heavy metal, a colloid-like matter, or the like included in an extremely minute amount in ultra-pure water to be used as rinsing water in a semiconductor cleaning process, and can restrict adherence on a substrata surface of the impurities, such as fine particles, a heavy metal or the like which deteriorate device characteristics. SOLUTION: In this cleaner, rinsing is performed with ultra-pure water as a rinsing liquid by supplying the ultra-pure water to a use point inside the apparatus via a pipe 7, and there is provided, in the middle of the pipe located inside the apparatus, a module 20 in which a porous film retained inside a film is filled with a polymer chain having an anion-exchange radical, a cation- exchange radical, or a chelate-forming radical. For the rinsing liquid, hydrogen containing ultra-pure water containing hydrogen is preferred.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method and an apparatus for preventing the adhesion of metal, especially as a trace amount of impurities in ultrapure water, in a wet cleaning process in the semiconductor industry.

[0002]

2. Description of the Related Art Immediately before a point of use, a porous membrane having an average pore diameter of 0.01 to 1 μm (hereinafter, referred to as a porous membrane) holding a polymer chain having a cation exchange group, an anion exchange group and a chelate-forming group in order to reduce impurities such as heavy metals Each is called a cation adsorption membrane, an anion adsorption membrane and a chelate membrane,
Further, it has been devised to introduce an ion-adsorbing membrane module filled with these three components collectively as an ion-adsorbing membrane immediately before the point of use (Japanese Patent Laid-Open No. 8-89954).

[0003] Hollow fiber membrane modules having a cation exchange group are adapted for removing metals, and particularly good for removing alkali metals and alkaline earth metals.

In a hollow fiber membrane module having an anion exchange group, fine particles and colloidal substances can be efficiently removed.

A hollow fiber membrane module having a chelate-forming group has an excellent function for removing heavy metals to an extremely low concentration.

It is known that the use of hydrogenated ultrapure water can suppress the attachment of fine particles to a substrate such as silicon, and can remove the attached particles. No. 10713 discloses that by treating a wafer with hydrogen in water or ultrapure water containing hydrogen and a rare gas, the removal rate of hydrocarbons is extremely high and the substrate can be easily terminated with hydrogen. Techniques are disclosed.

Since hydrogenated ultrapure water has an extremely high hydrocarbon removal rate, when rinsing is performed using hydrogenated ultrapure water, rinsing is performed using ultrapure water to which hydrogen is not added. A cleaner wafer surface should be obtained than would be the case.

However, when rinsing is performed using hydrogenated ultrapure water, a film formed on a silicon substrate (eg, an insulating film such as a gate insulating film) and an ultrapure water to which hydrogen is not added are used. The present inventor has found that when comparing the characteristics with the film formed on the rinsed substrate, the former film may have a lower quality (for example, dielectric strength) than the latter film. .

[0009] When the cause was sought, hydrogenated ultrapure water had the ability to remove fine particles and the effect of preventing the fine particles from adhering to the substrate, but made it easier for metal impurities to adhere to the substrate. It has been found that it has an effect. This is the deterioration of film quality (for example, deterioration of dielectric strength)
It is clarified that this is the cause of

[0010]

An object of the present invention is to remove impurities such as heavy metals and colloidal substances contained in a very small amount in ultrapure water used as rinsing water in a semiconductor cleaning process to improve device characteristics. It is an object of the present invention to provide a wet cleaning apparatus capable of suppressing adhesion of impurities, such as fine particles and heavy metals, to a substrate surface.

[0011]

According to the present invention, there is provided a wet cleaning apparatus comprising:
In a wet cleaning apparatus that performs rinsing with ultrapure water as a rinsing liquid by supplying ultrapure water to a use point inside the apparatus through a pipe, an anion exchange group, a cation exchange group or A module filled with a porous membrane in which a polymer chain having a chelate-forming group is held inside the membrane is provided.

Here, the term "cleaning device" refers to a multi- or single-tank batch cleaning device or a single-wafer cleaning device for performing wet cleaning. In wet cleaning, the surface of a wafer is made of ultrapure water. This is an apparatus that cleans the surface of the wafer with ultrapure water and finally drys the wafer surface. Note that a cleaning apparatus of a type in which cleaning is performed by injecting ultrapure water is also included.

Here, the cleaning apparatus includes a wet bench. The wet bench is a washing point equipped with exhaust equipment, and is a washing equipment provided with a supply pipe for ultrapure water or a chemical solution and a pipe for draining the washing liquid or rinse water.

The ultrapure water produced by the ultrapure water system is constantly circulated through the main loop and is withdrawn from the main loop by a necessary amount as dilution water of a chemical solution required for cleaning or rinse water by a branch pipe.

Branch pipes are drawn into the cleaning apparatus and the wet bench, and ultrapure water is supplied to each of the cleaning steps. In the final rinse, which is the final step of the cleaning step, a semiconductor substrate that has been cleaned and adhered is attached. The goal is to get rid of the chemicals you are using.

Here, the final rinse is defined as IPA (2-
(Propanol) refers to a step of rinsing chemicals adhering to the wafer surface with ultrapure water or hydrogenated ultrapure water immediately before the wafer drying step such as steam drying, spin drying or Marangoni drying.

Since the rinsing itself with ultrapure water has no effect of suppressing the adhesion of impurities such as metals, it is necessary for the rinsing water after chemical cleaning to remove even trace amounts of impurities.

In particular, in the final step of the wet cleaning, the substrate surface is etched with a dilute hydrofluoric acid solution to expose the bare silicon surface on which no oxide film is present, followed by a rinsing step of ultrapure water.

At this time, the purpose of the ultrapure water rinsing is to remove the hydrofluoric acid chemicals adhered to the substrate by rinsing with ultrapure water. If impurities such as metals exist in the ultrapure water, In this case, since the silicon surface is exposed, impurities may be attached.

Once impurities have been deposited on the substrate,
Ultrapure water has no ability to remove. Therefore, the ultrapure water used for the final rinse is required to contain no impurities such as metals that easily adhere to the substrate surface.

Metals among impurities present in ultrapure water are particularly reduced, and can be detected even by using a highly sensitive instrument analyzer such as an inductively coupled plasma mass spectrometer (ICP-MS). It's getting harder.

It is presumed that the presence of impurities at a level lower than the lower limit of quantification of the analytical instrument causes the attachment of impurities to the substrate surface.

Most of the metals present in ultrapure water are generally cations. However, they do not exist as cations alone but electrostatically interact with negatively charged silica or organic substances. It is presumed that it forms a weak bond and forms a cluster or colloid.

For this reason, in an apparatus for removing metal impurities in an ultrapure water system such as ion exchange or reverse osmosis, it is difficult to remove clustered substances having a small charge and a small size. It has been found that these metal impurities may be present and adhere to the substrate surface.

Here, by using a module filled with an ion-adsorbing membrane holding a polymer chain having an anion-exchange group or a cation-exchange group or a chelate-forming group, a clustered metal which cannot be removed by the conventional system is used. It has been found by the inventor's research that impurities such as can be removed.

The ion-adsorbing membrane used in the present invention is, for example, a hollow fiber-like porous membrane in which a polymer chain having an ion-exchange group is retained inside the membrane. A hollow fiber porous membrane having a milliequivalent ion exchange group and having an average pore size of 0.01 to 1 μm is preferably used.

Details of the production method and the like are as described in JP-A-8-89954.

The anion adsorption film has, for example, a quaternary amine as an exchange group and is generally obtained by quaternizing chloromethylstyrene. However, a nitrogen atom of a heterocyclic ring such as pyridine or imidazole is used. Can also be used.

In the cation adsorption membrane, sulfonic acid groups, phosphoric acid groups, carboxyl groups and the like are used as exchange groups.

In the chelate-forming group, an iminodiacetic acid group, a mercapto group, ethylenediamine or the like is used as an exchange group.

As a wet cleaning method in semiconductor manufacturing, a cleaning method called RCA cleaning as shown in FIG. 1 has been used from the past.

The RCA cleaning is characterized by mixing with an acid or an alkali based on hydrogen peroxide and cleaning at a high temperature, and is a process of repeatedly performing ultrapure water rinsing following chemical cleaning.

The role of the ultrapure water rinsing is nothing but removing the used chemicals from the substrate. However, in the rinsing step, impurities other than the chemicals can hardly be removed, so that purified ultrapure water is supplied. It is necessary.

[0034] Especially when contamination occurs in the final rinse, it is necessary to redo the entire cleaning process.
Care must be taken against recontamination.

In order to improve the quality of the ultrapure water used in the final rinse, these ion adsorption membrane modules are incorporated into the final rinse ultrapure water pipe in the cleaning apparatus, thereby causing a problem of poor cleaning in wet cleaning. Can be solved.

For example, in the case of cleaning a silicon wafer for manufacturing a semiconductor, when hydrogenated ultrapure water is used in a rinsing step of wet cleaning, first, ultrapure water is used as an exchange group inside the film to form an anion exchange group and cation exchange It is an object of the present invention to provide a cleaning method and apparatus characterized by adding hydrogen after treating with a module packed with an ion-adsorbing membrane holding a polymer chain having a group and a chelate-forming group.

Hydrogenated ultrapure water has the ability to remove fine particles adhering to the substrate and the effect of preventing the fine particles from adhering to the substrate, but has the problem that if metal impurities are present, they tend to adhere to the substrate. is there.

It has been found that if the metal impurities present in the ultrapure water are sufficiently reduced, the adhesion of the metal to the substrate can be suppressed even when the hydrogenated ultrapure water is used.

Therefore, according to the present invention, it is possible to suppress not only adhesion of fine particles but also adhesion of metal impurities. As a result, an insulating film having a high withstand voltage can be formed on the substrate even when the final rinse is performed by the wet cleaning apparatus of the present invention.

Accordingly, a cleaning method and apparatus characterized by treating with a module filled with an ion-adsorbing film to sufficiently reduce metal impurities from ultrapure water and then adding hydrogen thereto has been invented.

Further, for example, in the case of cleaning a silicon wafer for manufacturing a semiconductor, when hydrogenated ultrapure water is used in a rinsing step of wet cleaning, an exchange group is added inside the film after hydrogen is added to the ultrapure water. Can be treated with a module packed with an ion-adsorbing membrane holding a polymer chain having an anion exchange group, a cation exchange group and a chelate-forming group.

For example, when a silicon wafer is washed to produce a semiconductor, any one of a module filled with an ion-adsorbing membrane holding a polymer chain having an anion exchange group, a cation exchange group, or a chelate-forming group. A combination of two or more of them can be used in a washing apparatus or in a pipe of a wet bench.

Metals present in ultrapure water are ionized themselves and become cations, but substances such as silica and organic acids with negative charges approach the metal. They are clustered and exist in a colloidal state.

Since the charge bias varies depending on the type of the metal element or the mating silica or organic substance,
In some cases, it is not possible to completely remove the metal with one membrane module, but by combining membranes with different exchange groups introduced at this time, the metal can be completely removed. The combination method is as follows:-cation adsorption film + anion adsorption film-chelate film + anion adsorption film-anion adsorption film + cation adsorption film-anion adsorption film + chelate film-cation adsorption film + chelate film-chelate film + cation adsorption film・ Cation adsorption membrane + chelate membrane + anion adsorption membrane ・ Chelate membrane + cation adsorption membrane + anion adsorption membrane ・ Cation adsorption membrane + anion adsorption membrane + chelate membrane ・ Anion adsorption membrane + cation adsorption Membrane + chelate membrane ・ Anion adsorption membrane + chelate membrane + cation adsorption membrane ・ There is a method of combining three types of membranes such as chelate membrane + anion adsorption membrane + cation adsorption membrane. preferable.

The addition of hydrogen to ultrapure water may be performed upstream of the module, or may be performed downstream of the module. Performing the process upstream can more effectively prevent metal from adhering to the substrate. The hydrogen-containing ultrapure water includes:
This includes not only the case where hydrogen is added from the outside but also the case where hydrogen is contained from the beginning of production.

[0046]

EXAMPLE In the examples, an anion adsorption film, a cation adsorption film and / or a chelate film were used as the ion adsorption film. These ion-adsorbing membranes are described in T. Hori et al., Journal of Membr
It was prepared by the method described in ane Science 132 (1997) 203 211.

The anion adsorption membrane has a structure in which a polymer chain obtained by introducing a strongly basic quaternary ammonium type ion exchange group into a copolymer of chloromethylstyrene and divinylbenzene is fixed on the surface of a hollow fiber porous membrane.

The cation adsorption membrane has a structure in which a polymer chain obtained by introducing a strongly acidic sulfonic acid type ion exchange group into a copolymer of styrene and divinylbenzene is fixed on the surface of a hollow fiber porous membrane.

The chelate membrane has a structure in which a polymer chain obtained by introducing an iminodiacetic acid group into a copolymer of glycidyl methacrylate and divinylbenzene is fixed on the surface of a hollow fiber porous membrane.

[0050]

[Embodiment 1] FIG. 2 shows a cleaning apparatus for performing room temperature wet consisting of five steps.
~ 5. In the cleaning tank 1, cleaning with ozone ultrapure water is performed, and in the cleaning tank 2, cleaning is performed by adding a surfactant to a mixed solution of hydrofluoric acid and hydrogen peroxide and irradiating megasonic.

The cleaning tank 3 performs cleaning with ozone ultrapure water, the cleaning tank 4 performs dilute hydrofluoric acid treatment, and the cleaning tank 5 performs final ultrapure water rinsing.

Ultrapure water is supplied from the ultrapure water pipe 7 to the cleaning tank 1 and the cleaning tank 3, and ozone generated by the ozone generator 6 is mixed and dissolved in the ozone supplied from the pipe 13 by the pipe. It is supplied into the cleaning tank as ultrapure water.

The washing tank 2 is provided with a mixing tank 8.
The necessary chemicals are appropriately supplied to the mixing tank 8 from the hydrofluoric acid measuring tank 10 containing the surfactant and the hydrogen peroxide measuring tank 11, and the mixed chemical is transferred from the mixing tank 8 to the cleaning tank 2.

The washing tank 4 is provided with a mixing tank 9.
The necessary chemicals are appropriately supplied from the hydrofluoric acid measuring tank 12 to the mixing tank 9, and the mixed chemicals are transferred from the mixing tank 9 to the cleaning tank 4.

Ultrapure water is supplied to the cleaning tank 5 (use point in final rinse) from an ultrapure water pipe 7.
The dissolved oxygen concentration in this ultrapure water was 2 μg / L.

In the branch pipe inside the washing machine that supplies ultrapure water to the washing tank 5, between the supply outlet to the washing tank and the membrane filter for removing 0.1 μm fine particles, the anion adsorption membrane module 20 is used as the ion adsorption membrane module 20. , And the ultrapure water is completely filtered by the module 20 to perform the cleaning tank 5.
Was introduced.

First, an n-type (100) crystal plane manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of the ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After rinsing, the silicon wafer is dried,
The amount of metallic impurities such as copper, iron and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 1.

[0060]

Example 2 In the same washing apparatus as in Example 1, ions were supplied between a supply outlet to the tank and a membrane filter for removing 0.1 μm fine particles in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5. A cation adsorption membrane module was introduced as the adsorption membrane module 20, and the ultrapure water was completely filtered by this module and introduced into the washing tank 5.

First, an 8-inch n-type (100) 8 to 12Ω
The cm silicon wafer was cleaned from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid.

Next, cleaning was performed by changing the rinsing time of ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After rinsing, the silicon wafer is dried,
The amount of metallic impurities such as copper, iron and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 1.

[0064]

Example 3 In the same washing apparatus as in Example 1, ions were supplied between a supply outlet to the tank and a membrane filter for removing 0.1 μm fine particles in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5. A membrane module having a chelate-forming group was introduced as the adsorption membrane module 20, and the ultrapure water was entirely filtered through this module and introduced into the washing tank 5.

First, an n-type (100) crystal plane manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After rinsing, the silicon wafer is dried,
The amount of metallic impurities such as copper, iron and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 1.

[0068]

Comparative Example 1 Ultrapure water was supplied using the same washing apparatus as in Example 1 without introducing an ion adsorption membrane module.

First, an n-type (100) crystal plane manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of the ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After the rinsing, the silicon wafer is dried.
The amount of metallic impurities such as copper, iron and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 1.

[0072]

[Comparative Example 2] An anion adsorption membrane module was used as the ion adsorption membrane module 20 in the same cleaning apparatus as in Example 1 but in a branch pipe for supplying ultrapure water to the cleaning tank 5 but in a pipe outside the cleaning machine. Then, the ultrapure water was completely filtered by this module and introduced into the washing tank 5.

First, an n-type (100) crystal plane manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After rinsing, the silicon wafer is dried,
The amount of metallic impurities such as copper, iron and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 1.

[0076]

Comparative Example 3 A cation adsorption membrane module was used as the ion adsorption membrane module 20 in the same cleaning apparatus as in Example 1 but in a branch pipe for supplying ultrapure water to the cleaning tank 5 but in a pipe outside the cleaning machine. Then, the ultrapure water was completely filtered by this module and introduced into the washing tank 5.

First, an n-type (100) crystal face manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After the rinsing, the silicon wafer is dried.
The amount of metallic impurities such as copper, iron and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 1.

[0080]

COMPARATIVE EXAMPLE 4 The same cleaning apparatus as in Example 1 has a chelating group as an ion-adsorbing membrane module 20 in a pipe outside the cleaning machine in a branch pipe for supplying ultrapure water to the cleaning tank 5. A membrane module was introduced, and ultrapure water was completely filtered through this module and introduced into the washing tank 5.

First, an n-type (100) crystal plane manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After rinsing, the silicon wafer is dried,
The amount of metallic impurities such as copper, iron and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 1.

[0084]

Embodiment 4 A washing tank 2 is provided with a mixing tank 8.
The necessary chemicals are appropriately supplied to the mixing tank 8 from the hydrofluoric acid measuring tank 10 containing the surfactant and the hydrogen peroxide measuring tank 11, and the mixed chemical is transferred from the mixing tank 8 to the cleaning tank 2.

The washing tank 4 is provided with a mixing tank 9.
The necessary chemicals are appropriately supplied from the hydrofluoric acid measuring tank 12 to the mixing tank 8, and the mixed chemicals are transferred from the mixing tank 9 to the cleaning tank 4.

Ultrapure water was supplied to the washing tank 5 from the ultrapure water pipe 7, and the dissolved oxygen concentration in the ultrapure water was 2 μg / L and the dissolved hydrogen concentration was 1 mg / L.

An ion-adsorbing membrane module 2 is provided between a supply outlet to the tank and a membrane filter for removing 0.1 μm fine particles in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5.
As 0, an anion adsorption membrane module was introduced, and ultrapure water was completely filtered through this module and introduced into the washing tank 5.

First, an n-type (100) crystal plane manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After rinsing, the silicon wafer is dried,
The amount of metal impurities such as copper, iron, and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 2.

[0091]

Embodiment 5 In the same washing apparatus as in Embodiment 4, in the branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5, ions are supplied between the supply outlet to the tank and the membrane filter for removing 0.1 μm fine particles. A cation adsorption membrane module was introduced as the adsorption membrane module 20, and the ultrapure water was completely filtered by this module and introduced into the washing tank 5.

First, an n-type (100) crystal plane manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After the rinsing, the silicon wafer is dried.
The amount of metal impurities such as copper, iron, and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 2.

[0095]

[Embodiment 6] The same washing apparatus as in Embodiment 4 is used. In the branch pipe inside the washing machine that supplies ultrapure water to the washing tank 5, ions are supplied between the supply outlet to the tank and the membrane filter for removing 0.1 μm fine particles. A membrane module having a chelate-forming group was introduced as the adsorption membrane module 20, and the ultrapure water was entirely filtered through this module and introduced into the washing tank 5.

First, an n-type (100) crystal plane manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After rinsing, the silicon wafer is dried,
The amount of metal impurities such as copper, iron, and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 2.

[0099]

Comparative Example 5 Ultrapure water was supplied using the same cleaning apparatus as in Example 4 without introducing an ion adsorption membrane module.

First, an n-type (100) crystal plane manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After the rinsing, the silicon wafer is dried.
The amount of metal impurities such as copper, iron, and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 2.

[0103]

[Embodiment 7] FIG. 3 shows a room-temperature wet cleaning apparatus comprising five steps. In a cleaning tank 1, cleaning is performed using ultrapure ozone water, and in a cleaning tank 2, a surfactant is added to a mixed solution of hydrogen fluoride and hydrogen peroxide. Washing is performed by irradiation with megasonic.

The cleaning tank 3 performs cleaning with ozone ultrapure water, the cleaning tank 4 performs dilute hydrofluoric acid treatment, and the cleaning tank 5 performs final ultrapure water rinsing.

The cleaning tank 1 and the cleaning tank 3 are supplied with ultrapure water from an ultrapure water pipe 7, and ozone generated by an ozone generator 6 is mixed and dissolved in the pipe with ozone supplied from a pipe 13. It is supplied into the cleaning tank as ultrapure water.

The washing tank 2 is provided with a mixing tank 8.
The necessary chemicals are appropriately supplied to the mixing tank 8 from the hydrofluoric acid measuring tank 10 containing the surfactant and the hydrogen peroxide measuring tank 11, and the mixed chemical is transferred from the mixing tank 8 to the cleaning tank 2.

The washing tank 4 is provided with a mixing tank 9.
The necessary chemicals are appropriately supplied from the hydrofluoric acid measuring tank 12 to the mixing tank 8, and the mixed chemicals are transferred from the mixing tank 9 to the cleaning tank 4.

Ultrapure water was supplied to the cleaning tank 5 from the ultrapure water pipe 7, and the dissolved oxygen concentration in the ultrapure water was 2 μg / L.

In the branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5, between the supply outlet to the tank and the membrane filter for removing 0.1 μm fine particles, the ion adsorption membrane module 2
At 0, an anion adsorption membrane module was introduced, followed by a hydrogen dissolution membrane module 19 using polyolefin hollow fibers.

The dissolved hydrogen concentration is 1 in the hydrogen dissolving membrane module.
Hydrogen gas was added so as to be mg / L.

First, an n-type (100) crystal plane manufactured by an 8-inch diameter pulling-up method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After rinsing, the silicon wafer is dried,
The amount of metal impurities such as copper, iron and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 3.

[0114]

Example 8 In the same apparatus as in Example 7, a cation adsorption membrane module was introduced as an ion adsorption membrane module 20, and subsequently, a hydrogen dissolving membrane module 19 using polyolefin hollow fibers was introduced.

When the dissolved hydrogen concentration is 1
Hydrogen gas was added so as to be mg / L.

First, an n-type (100) crystal plane manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of the ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After the rinsing, the silicon wafer is dried.
The amount of metal impurities such as copper, iron and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 3.

[0119]

Example 9 In the same apparatus as in Example 7, a membrane module having a chelate-forming group was introduced as an ion-adsorbing membrane module 20, followed by a hydrogen dissolving membrane module 19 using polyolefin hollow fibers.

The dissolved hydrogen concentration is 1 in the hydrogen dissolving membrane module.
Hydrogen gas was added so as to be mg / L.

First, an n-type (100) crystal plane manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After the rinsing, the silicon wafer is dried.
The amount of metal impurities such as copper, iron and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 3.

[0124]

Comparative Example 6 The same apparatus as in Example 7 was introduced into a hydrogen dissolving membrane module 19 using a polyolefin hollow fiber without providing an ion-adsorbing membrane in a pipe supplied to the cleaning tank 5.

When the dissolved hydrogen concentration is 1 in the hydrogen dissolving membrane module
Hydrogen gas was added so as to be mg / L.

First, an n-type (100) crystal face manufactured by an 8-inch diameter pulling method (cz) and having a resistivity of 8
The cleaning of a silicon wafer of １２12 Ω · cm from cleaning tank 1 with ultrapure ozone water to cleaning tank 4 with dilute hydrofluoric acid was performed.

Next, cleaning was performed by changing the rinsing time of ultrapure water in the cleaning tank 5 to 10 minutes, 1, 3, and 7 days.

After the rinsing, the silicon wafer is dried.
The amount of metal impurities such as copper, iron and nickel among the attached impurities was measured by a total reflection X-ray fluorescence spectrometer, and the results are shown in Table 3.

[0129]

[Embodiment 10] Fig. 4 shows a room-temperature wet cleaning apparatus comprising five steps. A cleaning tank 1 is used for cleaning with ultrapure ozone water, and a cleaning tank 2 is provided with a surfactant in a mixed solution of hydrogen fluoride and hydrogen peroxide. Washing is performed by irradiation with megasonic.

The cleaning tank 3 performs cleaning with ozone ultrapure water, the cleaning tank 4 performs dilute hydrofluoric acid treatment, and the cleaning tank 5 performs final ultrapure water rinsing.

Ultrapure water is supplied to the cleaning tank 1 and the cleaning tank 3 from the ultrapure water pipe 7, and ozone generated by the ozone generator 6 is mixed and dissolved in the pipe with ozone supplied from the pipe 13. It is supplied into the cleaning tank as ultrapure water.

The washing tank 2 is provided with a mixing tank 8.
The necessary chemicals are appropriately supplied to the mixing tank 8 from the hydrofluoric acid measuring tank 10 containing the surfactant and the hydrogen peroxide measuring tank 11, and the mixed chemical is transferred from the mixing tank 8 to the cleaning tank 2.

The washing tank 4 is provided with a mixing tank 9.
The necessary chemicals are appropriately supplied from the hydrofluoric acid measuring tank 12 to the mixing tank 8, and the mixed chemicals are transferred from the mixing tank 9 to the cleaning tank 4.

Ultrapure water was supplied to the washing tank 5 from the ultrapure water pipe 7, and the concentration of dissolved oxygen in the ultrapure water was 2 μg / L.

A cation adsorption membrane module 20 was introduced between a supply outlet to the tank and a membrane filter for removing 0.1 μm fine particles in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5, and then an anion was added. The adsorption membrane modules 21 were introduced, and ultrapure water was completely filtered by these modules and introduced into the washing tank 5.

Using this cleaning machine, a MOS diode having a gate oxide film thickness (4.5 nm) was formed.

Element area 1 × 10 ⁻⁴ cm ² , judgment current value 1
Table 4 shows the results obtained by conducting a dielectric breakdown characteristic test of the MOS diode at × 10 ^-4 A and examining the average value of the dielectric breakdown voltage of the element (100 elements).

[0138]

[Embodiment 11] In the same apparatus as in Embodiment 10, chelate adsorption between a supply outlet to the tank and a membrane filter for removing 0.1 μm fine particles in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5. The membrane module 20 was introduced, and then the anion adsorption membrane module 21 was introduced. Ultrapure water was completely filtered through these modules and introduced into the washing tank 5.

Using this washer, a MOS diode having a gate oxide film thickness (4.5 nm) was prepared.

Element area 1 × 10 ⁻⁴ cm ² , judgment current value 1
Table 4 shows the results obtained by conducting a dielectric breakdown characteristic test of the MOS diode at × 10 ^-4 A and examining the average value of the dielectric breakdown voltage of the element (100 elements).

[0141]

Embodiment 12 Using the same apparatus as in Embodiment 10, anion adsorption between a supply outlet to the tank and a membrane filter for removing 0.1 μm fine particles in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5. The membrane module 20 was introduced, and then the chelate adsorption membrane module 21 was introduced. Ultrapure water was completely filtered by these modules and introduced into the washing tank 5.

Using this washing machine, a MOS diode having a gate oxide film thickness (4.5 nm) was formed.

Element area 1 × 10 ⁻⁴ cm ² , judgment current value 1
Table 4 shows the results obtained by conducting a dielectric breakdown characteristic test of the MOS diode at × 10 ^-4 A and examining the average value of the dielectric breakdown voltage of the element (100 elements).

[0144]

Example 13 In the same apparatus as in Example 10, cation was adsorbed between a supply outlet to the tank and a membrane filter for removing 0.1 μm fine particles in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5. The membrane module 20 was introduced, and then the chelate adsorption membrane module 21 was introduced. Ultrapure water was completely filtered by these modules and introduced into the washing tank 5.

Using this washer, a MOS diode having a gate oxide film thickness (4.5 nm) was formed.

Element area 1 × 10 ⁻⁴ cm ² , judgment current value 1
Table 4 shows the results obtained by conducting a dielectric breakdown characteristic test of the MOS diode at × 10 ^-4 A and examining the average value of the dielectric breakdown voltage of the element (100 elements).

[0147]

Example 14 The same apparatus as in Example 10 was used to adsorb anions between the supply outlet to the tank and a membrane filter for removing 0.1 μm fine particles in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5. Only the membrane module 20 was introduced, and ultrapure water was completely filtered by these modules and introduced into the washing tank 5.

Using this cleaning machine, a MOS diode having a gate oxide film thickness (4.5 nm) was formed.

Element area 1 × 10 ⁻⁴ cm ² , judgment current value 1
Table 4 shows the results obtained by conducting a dielectric breakdown characteristic test of the MOS diode at × 10 ^-4 A and examining the average value of the dielectric breakdown voltage of the element (100 elements).

[0150]

[Embodiment 15] Fig. 5 shows a wet cleaning apparatus at room temperature consisting of five steps. A cleaning tank 1 is used for cleaning with ultrapure ozone water, and a cleaning tank 2 is provided with a surfactant in a mixed solution of hydrogen fluoride and hydrogen peroxide. Washing is performed by irradiation with megasonic.

In the cleaning tank 3, cleaning with ozone ultrapure water is performed, in the cleaning tank 4, dilute hydrofluoric acid treatment is performed, and in the cleaning tank 5, final ultrapure water rinsing is performed.

Ultrapure water is supplied from the ultrapure water pipe 7 to the cleaning tanks 1 and 3, and ozone generated by the ozone generator 6 is mixed and dissolved in the ozone supplied from the pipe 13 by the pipes. It is supplied into the cleaning tank as ultrapure water.

The washing tank 2 is provided with a mixing tank 8.
The necessary chemicals are appropriately supplied to the mixing tank 8 from the hydrofluoric acid measuring tank 10 containing the surfactant and the hydrogen peroxide measuring tank 11, and the mixed chemical is transferred from the mixing tank 8 to the cleaning tank 2.

The washing tank 4 is provided with a mixing tank 9.
The necessary chemicals are appropriately supplied from the hydrofluoric acid measuring tank 12 to the mixing tank 8, and the mixed chemicals are transferred from the mixing tank 9 to the cleaning tank 4.

Ultrapure water was supplied to the cleaning tank 5 from the ultrapure water pipe 7, and the concentration of dissolved oxygen in the ultrapure water was 2 μg / L.

A cation adsorption membrane module 20 was introduced between a supply outlet to the tank and a membrane filter for removing 0.1 μm fine particles in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5, The membrane module 21 having a forming group and the anion adsorption membrane module 22 were further introduced, and the ultrapure water was completely filtered by these modules and introduced into the washing tank 5.

Using this washing machine, a MOS diode having a gate oxide film thickness (3.5 nm) was formed.

Element area 1 × 10 ⁻⁴ cm ² , judgment current value 1
Table 5 shows the results of conducting a dielectric breakdown characteristic test of a MOS diode at × 10 ⁻⁴ A and examining the average value of the dielectric breakdown voltage of the element (100 elements).

[0159]

Embodiment 16 In the same apparatus as in Embodiment 14, a chelate is formed between a supply outlet to the tank and a membrane filter for removing fine particles of 0.1 μm in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5. A membrane module 20 having a group was introduced, a cation adsorption membrane module 21 was further introduced, and an anion adsorption membrane module 22 was further introduced. Ultrapure water was completely filtered through these modules and introduced into the washing tank 5.

Using this washing machine, a MOS diode having a gate oxide film thickness (3.5 nm) was formed.

Element area 1 × 10 ⁻⁴ cm ² , judgment current value 1
Table 5 shows the results of conducting a dielectric breakdown characteristic test of a MOS diode at × 10 ⁻⁴ A and examining the average value of the dielectric breakdown voltage of the element (100 elements).

[0162]

Embodiment 17 In the same apparatus as in Embodiment 14, a chelate is formed between a supply outlet to the tank and a membrane filter for removing 0.1 μm fine particles in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5. A membrane module 20 having a base was introduced, followed by an anion adsorption membrane module 21 and further a cation adsorption membrane module 22. Ultrapure water was completely filtered through these modules and introduced into the washing tank 5.

Using this washing machine, a MOS diode having a gate oxide film thickness (3.5 nm) was prepared.

Element area 1 × 10 ⁻⁴ cm ² , judgment current value 1
Table 5 shows the results of conducting a dielectric breakdown characteristic test of a MOS diode at × 10 ⁻⁴ A and examining the average value of the dielectric breakdown voltage of the element (100 elements).

[0165]

Example 18 The same apparatus as in Example 14 was used to adsorb cations between a supply outlet to the tank and a membrane filter for removing 0.1 μm fine particles in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5. The membrane module 20 was introduced, the anion adsorption membrane module 21 was further introduced, and the membrane module 22 having a chelating group was further introduced. Ultrapure water was completely filtered through these modules and introduced into the washing tank 5.

Using this washing machine, a MOS diode having a gate oxide film thickness (3.5 nm) was formed.

Element area 1 × 10 ⁻⁴ cm ² , judgment current value 1
Table 5 shows the results of conducting a dielectric breakdown test of a MOS diode at × 10 ^-4 A and examining the average value of the dielectric breakdown voltage of the element (100 elements).

[0168]

Example 19 The same apparatus as in Example 10 was used to adsorb anion between a supply outlet to the tank and a membrane filter for removing 0.1 μm fine particles in a branch pipe inside the washing machine for supplying ultrapure water to the washing tank 5. The membrane module 20 was introduced, and then the cation adsorption membrane module 21 was introduced. Ultrapure water was completely filtered through these modules and introduced into the washing tank 5.

Using this washing machine, a MOS diode having a gate oxide film thickness (3.5 nm) was prepared.

Element area 1 × 10 ⁻⁴ cm ² , judgment current value 1
Table 5 shows the results of conducting a dielectric breakdown characteristic test of a MOS diode at × 10 ⁻⁴ A and examining the average value of the dielectric breakdown voltage of the element (100 elements).

[0171]

[Table 1]

[0172]

[Table 2]

[0173]

[Table 3]

[0174]

[Table 4]

[0175]

[Table 5]

[0176]

According to the present invention, it is possible to remove the clustered metal (silica and organic substances, which have been weakened in charge by clustering) which could not be removed by the conventional ultrapure water production apparatus, and it is possible to remove the wet process, especially the rinsing. In this case, the amount of metal adhering to the substrate can be reduced.

In order to reduce the amount of metal adhering to the substrate, an element defect (fail bit) caused by the wet process
Can be expected to be reduced.

[Brief description of the drawings]

FIG. 1 is a process chart showing a cleaning procedure.

FIG. 2 is a conceptual diagram illustrating a cleaning system used in Example 1.

FIG. 3 is a conceptual diagram showing a cleaning system used in Example 4.

FIG. 4 is a conceptual diagram showing a cleaning system used in Example 10.

FIG. 5 is a conceptual diagram showing a cleaning system used in Example 15.

[Explanation of symbols]

 1, 2, 3, 4, 5 cleaning tank, 6 ozone generator, 7 ultrapure water pipe, 8 mixing tank, 9 mixing tank, 10, 12 hydrofluoric acid measuring tank, 11 hydrogen light tank, 13 pipe, 19 Hydrogen dissolving membrane module, 20, 21, 22 Ion adsorption module.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 16, 2000 (2000.2.1
6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction contents]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a process for cleaning a very small amount of impurities in ultrapure water in a wet cleaning process in the semiconductor industry .
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning device for preventing adhesion , and more particularly to a cleaning device for preventing adhesion of metal.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshihiro Ii 05 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi Prefecture Tohoku University ) Inventor Noboru Kubota 2-1 Samejima, Fuji City, Shizuoka Prefecture In-house (72) Inventor Tadahiro Omi 2-17-17 301 Yonegabukuro, Aoba-ku, Sendai City, Miyagi Prefecture

Claims (6)

[Claims] In a wet cleaning apparatus for rinsing ultrapure water as a rinsing liquid by supplying ultrapure water to a use point inside the apparatus through a pipe, an anion exchange group is provided on the way of the pipe located inside the apparatus. A wet-washing device, comprising a module filled with a porous membrane in which a polymer chain having a cation exchange group or a chelate-forming group is held inside the membrane. 2. The wet cleaning apparatus according to claim 1, wherein the rinsing liquid is hydrogen-containing ultrapure water containing hydrogen. 3. The wet cleaning apparatus according to claim 2, wherein a hydrogen adding means is provided downstream of the module. 4. The wet cleaning apparatus according to claim 2, wherein a hydrogen adding means is provided upstream of the module. 5. A module filled with a porous membrane holding a polymer chain having an anion exchange group, a module packed with a porous membrane holding a polymer chain having a cation exchange group, or a polymer having a chelate-forming group. The wet cleaning apparatus according to any one of claims 1 to 4, wherein at least two or more modules packed with a porous membrane holding chains are provided in combination. The above-described cleaning method and apparatus, wherein the processing is performed continuously. 6. The wet cleaning apparatus according to claim 1, wherein the rinse is a final rinse.